Abstract: A digital video encoder is presented adapted for dynamically switching between sets of quantizer matrix tables without pausing encoding of a stream of video data. Two or more sets of quantizer matrix tables are held at the encoder's quantization unit and compressed store interface for dynamically switching between sets of quant matrix tables at a picture boundary of the sequence of video data, i.e., without stopping encoding of the sequence of video data. Further, while one set of matrix tables is being employed to quantize the stream of video data, the encoder can be updating or modifying another set of quantization matrix tables, again without stopping encoding of the sequence of video data.

Abstract: An MPEG2 compliant digital video encoder system employs an I-frame video encoder module having a quantization unit and variable length encoding to encode coefficients of each macroblock of a picture. Bit regulation schemes are presented for constraining selected coefficients of a macroblock if the bit rate of two prior macroblocks in a row exceeded a bit rate limit, or if the bit rate of the current nonintra macroblock is greater than a predetermined megabits per second (Mbps) limit. Pattern constraining is implemented within the quantization unit. For nonintra pictures, the conventional variable length coding process is modified to generate a Fixed Coded Block Pattern (FCBP) header for each macroblock of the picture for outputting in the bitstream prior to coding of the coefficients. The FCBP signifies that each block of the macroblock contains at least one nonzero coefficient.